This application claims the priority of Korean Patent Application No. 10-2004-0081500, filed on Oct. 12, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates generally to a semiconductor device and a method of manufacturing the same, and more particularly to a semiconductor device capable of increasing an aperture ratio of an organic electroluminescence display device by decreasing a surface area of a capacitor in the organic electroluminescence display device, and a method of manufacturing the semiconductor device.
2. Description of the Related Technology
In flat panel display devices, such as active matrix organic electroluminescence display devices, also known as organic light emitting diode (OLED) displays, each unit pixel comprises (1) a thin film transistor connected to a gate line, a data line, and a power supply line, (2) a capacitor, and (3) an organic electroluminescence element. The capacitor is formed at the same time as forming the gate line, a gate electrode, the data line, source/drain electrodes, and the power supply line. In such flat panel display devices, a method of increasing the surface area of the capacitor, a method of decreasing the thickness of a dielectric film formed between electrodes of the capacitor, or a method of employing a dielectric film having a high dielectric constant is typically used to enhance the capacitance of the capacitor. However, the method of increasing the surface area of the capacitor may lead to a decrease in aperture ratio, and the method of decreasing the thickness of the dielectric film requires an additional fabrication process, thereby increasing the number of processes required for manufacture.
FIG. 1 is a plan view illustrating an exemplary organic electroluminescence display device. Referring to FIG. 1, the active matrix organic electroluminescence display device comprises a plurality of gate lines 110, a plurality of data lines 120, a plurality of power supply lines 130, and a plurality of pixels connected to the gate lines 110, the data lines 120, and the power supply lines 130.
Each pixel comprises a switching thin film transistor (TFT) 170 connected to the corresponding gate line of the plurality of gate lines 110, and the corresponding data line of the plurality of data lines 120. Each pixel further comprises a driving TFT 150 configured to drive an electroluminescence element 160, wherein the driving TFT 150 is connected to the corresponding power supply line 130, a capacitor 140 configured to store the gate-source voltage of the driving TFT 150, and the electroluminescence element 160.
The driving TFT 150 comprises a semiconductor layer 152 having source and drain regions, a gate electrode 154, and source and drain electrodes 156a, 156b connected to the source and drain regions through contact holes 155a, 155b, respectively. The switching TFT 170 has the same structure as that of the driving TFT 150.
The capacitor 140 comprises a lower electrode 144 which is connected to one of the source and drain electrodes of the switching TFT 170 (the source electrode, for example) and the gate electrode of the driving TFT 150. The capacitor 140 further comprises an upper electrode 146 connected to one of the source and drain electrodes of the driving TFT 150 (the source electrode 156a, for example) and a common power supply line 130. Each pixel electrode 161, which is an anode electrode of the electroluminescence element having an opening, is connected to one of the source and drain electrodes 156a, 156b of the driving TFT 150 (the drain electrode 156b, for example) through a via hole 158.
In the exemplary organic electroluminescence display device described above, one pixel is divided into a non-light-emitting area provided with the TFTs and the capacitor and a light emitting area provided with the electroluminescence element. An increase in the non-light-emitting area correspondingly decreases the light emitting area. However, the capacitor occupies a relatively large area in the pixel, and a high-capacity capacitor is required for increased device integration. Therefore, with the increased area requirement for a high-capacity capacitor in a pixel, the light emitting area is reduced, thereby decreasing the aperture ratio of the organic electroluminescence display device.